Deset korun je malá úspora.

Because after 5 and higher numbers in Czech, the counted noun normally goes into the genitive plural.

• 1 koruna
• 2, 3, 4 koruny
• 5+ korun

So:

• deset korun = ten crowns / ten korunas

This is one of the most important number patterns in Czech.

Korun is the genitive plural of koruna.

The full phrase deset korun functions as the subject of the sentence, but inside that phrase the noun korun is still in the form required by the numeral deset.

So you can think of it like this:

• whole subject: deset korun
• noun form after the numeral: genitive plural

In Czech, an amount like deset korun is often treated as one quantity rather than as ten separate items.

So:

• Deset korun je málo. = Ten crowns is little.
• Deset korun je malá úspora. = Ten crowns is a small saving.

English sometimes does something similar:

• Ten dollars is not much.

So the singular verb makes sense because the phrase is understood as a single amount.

Because malá agrees with úspora, not with deset korun.

• úspora is a feminine singular noun
• therefore the adjective must also be feminine singular
• so: malá úspora

Compare:

• malý dům = masculine
• malá úspora = feminine
• malé město = neuter

Úspora means saving in the sense of:

• an amount saved
• a reduction in cost or use
• something economical

In this sentence, malá úspora means a small saving or a small amount saved.

It is a feminine noun:

• nominative singular: úspora
• genitive singular: úspory

Both ideas are involved, depending on what part you look at.

• The whole phrase deset korun is the subject, so it functions like a nominative subject phrase.
• But the noun korun itself is in the genitive plural, because that is what deset requires.

So a useful way to think about it is:

• sentence role of the phrase: subject
• grammatical form of the noun after the numeral: genitive plural

Yes. Czech word order is more flexible than English word order.

For example, you could also say:

• Malá úspora je deset korun.

But Deset korun je malá úspora is perfectly natural if you want to start with the amount.

Word order in Czech often depends on:

• emphasis
• topic vs. new information
• style

So the original version is fine and straightforward.

Because Czech has no articles like English a / an / the.

So:

• malá úspora can mean a small saving
• in another context, it could also mean the small saving

You understand which one is meant from the context, not from an article.

A simple learner-friendly approximation is:

• DEH-set KO-roon yeh MAL-aa OO-spo-ra

A few notes:

• deset = DEH-set
• korun = KO-roon
• je sounds like yeh
• malá has a long á
• úspora has a long ú

So the long vowels in malá and úspora should be held a bit longer than short vowels.

Yes, it is grammatical and natural enough, especially in a context about money or budgeting.

It sounds like a general statement such as:

• Ten crowns is a small saving.
• Saving ten crowns is only a small saving.

In real conversation, depending on context, a Czech speaker might also say things like:

• Deset korun je málo. = Ten crowns is not much.
• Je to malá úspora. = It’s a small saving.

But the sentence you have is completely correct.